Not all of us are walking encyclopedias of automotive knowledge. We all know that one guy who can rattle off facts like how many '67 small-window C10s were made, but does that knowledge really matter? Well, it may not help build a truck, but it is cool to know. We wanted to give you some information that you might be able to use in the real world and hopefully help you build a better truck. With the assistance of some of our four-wheel-drive buddies, we compiled a guide to help you determine what rearend is under the truck and what lug pattern it has. This will just cover truck stuff, but that doesn't mean a car rearend can't be stuffed under your S-10. But that's a story for another day. We hope you find this guide useful, and until next month: Keep your eyes on the rearend.

TECH TIP
Axle Terminology

To prevent you from looking like a total newbie, here's some techno-jargon terms you should know when talking to the guy behind the parts counter:

Semifloating: The weight of the vehicle rides on the axleshaft, which also spins the wheel.

Full-floating: The weight of the vehicle rides on the axlehousing, and a ring of bolts in the center holds the axleshaft in place.

Integral: The ring gear and pinion gear are set up inside the differential housing.

Dropout: The carrier, or differential, can be removed as a single unit. It is also called the centersection.

Chrysler 8-1/4
This semifloating rear axle features a 10-bolt cover and appeared in various Dodge and Jeep vehicles.
Applications: '90-'00 Dakota, '72-'96 1/2-ton 2WD and 4WD Dodge fullsize, '92-present Cherokee
Ring-gear diameter: 8.25 in
Pinion-gear diameter/splines: 1.626 in/27 splines
Available gearsets: 2.71, 2.94, 3.21, 3.55, 3.90, 4.10, and 4.56